Draft Policy ARIN-2025-1

Clarify ISP and LIR Definitions and References to Address Ambiguity in NRPM Text

Status: Under Discussion
Shepherds: Leif Sawyer, Elizabeth Goodson

Current Text (12 September 2025)

Problem Statement:

Section 2.4 of the NRPM defines an LIR but does not explicitly define an ISP. An ISP is defined in the context of an LIR, but the explicit definition is otherwise assumed.

Through implication and in common business practice, all ISPs are LIRs, but not all LIRs are ISPs.

This proposal adds clarity by creating an explicit definition for ISP, clarifying the historical and out-of-region usage for the term LIR, and replaces LIR with ISP throughout the NRPM as appropriate.

Policy Statement:

Add Internet Service Provider definition:

Remove the word “primarily” from the definition of LIR and add usage clarification:

FROM:

2.4. Local Internet Registry (LIR)

A Local Internet Registry (LIR) is primarily an IR that assigns IP addresses to the users of the network services that it provides. LIRs are generally Internet Service Providers (ISPs) whose customers are primarily end users and possibly other ISPs.

TO:

2.4. Local Internet Registry (LIR)

A Local Internet Registry (LIR) is an IR that assigns IP addresses to the users of the network services that it provides. LIRs are generally Internet Service Providers (ISPs) whose customers are primarily end users and possibly other ISPs. While LIR has been historically referenced in policies for ease of comparing other region’s policies, LIR is not used in the ARIN service region; ISP is the equivalent term.

Add definition for ISP:

2.18 Internet Service Provider (ISP)

An Internet Service Provider (ISP) is a type of organization that provides Internet services to other organizations, its customers, and\or individuals other than its employees. Internet services include, but are not limited to, connectivity services, web services, colocation, dedicated servers, virtual private servers, and virtual private networks.

Replace Section 6.5.1a

Original Text: “The terms ISP and LIR are used interchangeably in this document and any use of either term shall be construed to include both meanings.”

New Text: “[Retired]”

Remove all references in section 6.5 of LIR where appropriate:

[Editing note: For the purposes of clarity in plaintext communication mediums, any changes to the text is denoted with the underscore character before and after the insertion. The underscore character is not considered a part of the final text.]

Amend Section 6.5.2 to replace LIR with ISP, 12 in total

6.5.2. Initial Allocation to ISPs

6.5.2.1. Size

1. All allocations shall be made on nibble boundaries.

2. In no case shall an ISP receive smaller than a /32 unless they specifically request a /36 or /40. In order to be eligible for a /40, an ISP must meet the following requirements:

   • Hold IPv4 direct allocations totaling a /24 or less (to include zero)
   • Hold IPv4 reassignments/reallocations totaling a /22 or less (to include zero)

   In no case shall an ISP receive more than a /16 initial allocation.

3. The maximum allowable allocation shall be the smallest nibble-boundary aligned block that can provide an equally sized nibble-boundary aligned block to each of the requesters serving sites large enough to satisfy the needs of the requesters largest single serving site using no more than 75% of the available addresses.

   This calculation can be summarized as /N where N = P-(X+Y) and P is the organization’s Provider Allocation Unit X is a multiple of 4 greater than 4/3* serving sites and Y is a multiple of 4 greater than 4/3* end sites served by largest serving site.

4. For purposes of the calculation in (c), an end site which can justify more than a /48 under the end-user assignment criteria in  6.5.8 shall count as the appropriate number of /48s that would be assigned under that policy.

5. For purposes of the calculation in (c), an ISP which has subordinate ISPs shall make such reallocations according to the same policies and criteria as ARIN. In such a case, the prefixes necessary for such a reallocation should be treated as fully utilized in determining the block sizing for the parent ISP. ISPs which do not receive resources directly from ARIN will not be able to make such reallocations to subordinate ISPs and subordinate ISPs which need more than a /32 shall apply directly to ARIN.

6. An ISP is not required to design or deploy their network according to this structure. It is strictly a mechanism to determine the largest IP address block to which the ISP is entitled.

7. An ISP that requests a smaller /36 or /40 allocation is entitled to expand the allocation to any nibble aligned size up to /32 at any time without renumbering or additional justification. /40 allocations shall be automatically upgraded to /36 if at any time said ISP’s IPv4 direct allocations exceed a /24. Expansions up to and including a /32 are not considered subsequent allocations, however any expansions beyond /32 are considered subsequent allocations and must conform to section 6.5.3. Partial returns of any IPv6 allocation that results in less than a /36 of holding are not permitted regardless of the ISP’s current or former IPv4 address holdings.

Amend Section 6.5.3 to replace LIR with ISP in 4 locations:

6.5.3. Subsequent Allocations to ISPs

1. Where possible ARIN will make subsequent allocations by expanding the existing allocation.

2. An ISP qualifies for a subsequent allocation if they meet any of the following criteria:

   • Shows utilization of 75% or more of their total address space
   • Shows utilization of more than 90% of any serving site
   • Has allocated more than 90% of their total address space to serving sites, with the block size allocated to each serving site being justified based on the criteria specified in section 6.5.2

3. If ARIN can not expand one or more existing allocations, ARIN shall make a new allocation based on the initial allocation criteria above. The ISP is encouraged, but not required to renumber into the new allocation over time and return any allocations no longer in use.

4. If an ISP has already reached a /12 or more, ARIN will allocate a single additional /12 rather than continue expanding nibble boundaries.

Amend Section 6.5.4.1 to replace LIR with ISP in 1 location:

6.5.4.1. Reassignment to Operator’s Infrastructure

An ISP may reassign up to a /48 per PoP as well as up to an additional /48 globally for its own infrastructure.

Amend Section 6.5.7 to replace LIR with ISP in 1 location:

6.5.7. Existing IPv6 Address Space Holders

ISPs which received an allocation under previous policies which is smaller than what they are entitled to under this policy may receive a new initial allocation under this policy. If possible, ARIN will expand their existing allocation.

Amend Section 6.5.8 to remove “or other LIR” in 2 locations

6.5.8.1. Initial Assignment Criteria

FROM:

f. By providing a reasonable technical justification indicating why IPv6 addresses from an ISP or other LIR are unsuitable.

TO:

f. By providing a reasonable technical justification indicating why IPv6 addresses from an ISP are unsuitable.

FROM:

Examples of justifications for why addresses from an ISP or other LIR may be unsuitable include, but are not limited to:

TO:

Examples of justifications for why addresses from an ISP may be unsuitable include, but are not limited to:

Timetable for Implementation: Immediate.

Comments: This proposal was submitted after the abandonment of Proposal 2024-6, which proposed clarifying 6.5.1a’s language. The community feedback indicated a more explicit approach was desired to remove ambiguity, resulting in this follow up proposal.

The changes in Section 6.5 adding LIR or ISP were reviewed with the context of each reference in mind, and only those that clearly fit the contextual change of needing the “LIR/ISP” definition were included. This did not necessarily include every reference to LIR or ISP in Section 6.5

History and Earlier Versions

Related Meetings